While playing with RGB Panels, I wanted to fix 3 problems
protect my LEDs: when transporting the panels in luggage, the LEDs can be ripped out the board
add a protection around the board which is has very sharp corners (relevant on my shirt for dancing)
act as a diffuser so that the LEDs aren't as "sharp" in the dark, and generally act as a diffuser.
The diffuser however had to be:
reasonably light (it's for a wearable)
somewhat bendable and not easily breakable (again, wearable)
After getting recommendations on the FastLED group and SmartMatrix group, I ended up getting two things:
Extra Thick Flexible Frosted Clear Plastic Cutting Mat
Serenity Foam Underlayment for Laminate Flooring
The Frosted Clear Plastic Cutting Mat was good for protection, but didn't offer too much diffusion. Still, it was better than nothing, and that's what I ended up using in the front of my shirt.
The Serenity Foam Underlayment for Laminate Flooring offered better diffusion, but no protection at all. However, I figured out that if I used that, plus the cutting mat on top, I got extra diffusion and protection.
If you wonder, the demos below can be had from:
Here are pictures of what it looks like with one and both layers:
The cutting mat only still provides some diffusion, just not as much:
Here is what it looks like with both layers and very small wires to hold the mat on top of the 3 32x64 RGBPanels attached together:
Here is what it looks like side by side, with both, and without any:
This works pretty well, thank to the people who provided suggestions and help